question about the Smithy 516

[nachman]

Hi

This is my first post in this forum which I've already found to be very helfull. I'm interested in getting the Smithy 516 and convert it to servo drive. If anyone has this machine I would like to know the actuall mechanical positioning accuracy (how much backlash does it have under no load conditions). The specification says 0.01mm, but that might be after some backlash compensetion done by the program. It is a bit to good to be true for a machine that doesn't cost much and it's axes don't run on linear bearings.

Nachman

a link to the specification:

http://www.smithy.com/product_specs....id=16&pid=1007

[sansbury]

Why do you want to put servos on it?

[nachman]

I want to put servos on it because then I can add hand wheels and use it for manual operation as well. The motors encoders gives me digital readout and they can be turned smoothly by hand since they don't have the cogging a stepper motor has. I have a Wabeco 1210E at home that I'm runing this way for several years. I found it to be very convinient for prepering the raw material, alignment and initial postioning, and also for very simple machining tasks that goes faster without the need for toolpath programing.
I'm going to be living in the US for some time in about two months and I can't imegine mysellf with out a cnc ( and a few other tools I've got at home).

[mapex99]

I have the 622 which is a little bigger at the backlash without software compensation is on the order of 0.001" [0.0254 mm]. They use anti-backlash ballnuts but I don't know how good they are. It also could be coming from the angular contact bearing...

[philbur]

Two points:

Did the Wabeco have ballscrews or threaded leadscrews.

Secondly you can use a CNC machine manually without the need for any toolpath programing. Seems you need an MPG/pendant rather than servos.

Phil

Originally Posted by nachman I have a Wabeco 1210E at home that I'm runing this way for several years. I found it to be very convinient for prepering the raw material, alignment and initial postioning, and also for very simple machining tasks that goes faster without the need for toolpath programing. I'm going to be living in the US for some time in about two months and I can't imegine mysellf with out a cnc ( and a few other tools I've got at home).

[nachman]

Thanks for the info. 0.0254mm backlash is not to bad and I'll assume that the smaller 516 might have around the same backlash without backlash compensetion. I can live with that even though I was hopping for a bit less backlash. I still have time to shop around for something better but I doubt I'll find one. This one simply fit my needs, and even though it's not an important factor, I like the look of it .
The best machine I could wish for is one at this size and weight but with linear gides on all axes. This would be the ideal machine for me under the circumstances but so far I couldn't find such one.

[nachman]

The Wabeco came with ballscrews. It was cnc ready. They aren't that good though and I have about 0.04mm and 0,05mm anowing backlash on the x and y axes.
I'm not sure a pendant is as comfortable to use for manual operation as simply turning the axes directly. It gives you some feedback about what you're doing when you turn the axes with a hand wheel. Anyway, it's always an option.